Passivity Analysis of a motion control for robots manipulators with dynamic friction

This paper addresses the motion control in joint space of robot manipulators with friction described by the generalized LuGre friction model. The paper extends the nonadaptive version of the Slotine and Li’s control system originally designed for friction–free manipulators to the case where a friction observer is incorporated to deal with friction. This observer corresponds to an adaptation of the friction compensation scheme proposed in Canudas de Wit et al in 1975. Passivity concepts are the fundamental tools invoked in this paper to analyze the closed–loop system behavior which lead to the conclusion of global asymptotic joint position tracking. A major advantage of this framework is that it allows to develop in a separate way the control law from the observer design provided that each part satisfies some passivity properties.